Integrated multilayered microwave circuit

ABSTRACT

An integrated multi-layered microwave circuit includes a substrate which is constituted by dielectric layers and conductive layers laminated alternately. The conductive layer disposed at one major surface of the substrate forms a micro strip line which constitutes an antenna portion. The conductive layer disposed at the other major surface of the substrate forms a circuit pattern including a grounding line and a power source line, and then the circuit pattern forms a communication portion together with discrete parts incorporated in the circuit pattern. One of the intermediate conductive layers of the substrate constitutes a grounding layer and the other thereof constitutes a power source layer. In the substrate, a feeding via hole, a via hole for a power source, and a grounding via hole are formed so as to penetrate the substrate. Conductors are formed on the inner walls of the substrate forming the feeding via hole, the via hole for the power source, and the grounding via hole by the plating technique, respectively, whereby the antenna portion, the power source layer and the grounding layer are electrically connected to the communication portion, the power source line and the grounding line, respectively. The antenna portion is provided with a feeding land connected to the conductors of the feeding via hole, three radiators each having a circular configuration formed by the micro strip line, and a phase shifter formed by the micro strip line for connecting the respective radiators to the feeding land.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to integrated multi-layeredmicrowave circuits used in a mobile radio communication system utilizinga radio wave of a microwave band such as a vehicle information andcommunication systems (VICS) and, more particularly, is directed to anintegrated multi-layered microwave circuit and a method of fabricatingit which is easily miniaturized and has less signal loss.

2. Description of the Related Art

In the VICS, a vehicle antenna receives various information such as alocation of a vehicle or a road condition such as congestion which istransmitted from a terrestrial station such as a beacon provided on aroad, and various devices mounted on the vehicle are controlled based onthe received information. Further, it has been proposed to arrange theVICS so that the vehicle antenna transmits information from the variousdevices mounted on the vehicle to an external station such as the earthstation or another vehicle. The thus constituted VICS has been put topractical use as an example of the mobile radio communication systemsutilizing a radio wave of a microwave band. In particular, it has beenan important problem to be solved to miniaturize and decrease weight ina radio communication terminal for a mobile station which is mounted ina movable body (mobile) or vehicle and processes a signal received by avehicle antenna.

In a conventional circuit arrangement usable as the radio communicationterminal for the mobile station of the mobile radio communicationsystem, an antenna portion and a communication portion for processing asignal received by the antenna portion are provided separately, ingeneral, in order to freely position the antenna portion. That is, inalmost cases, the antenna portion and the communication portion arelocated at different portions. For example, in the prior art disclosedin JP-A-2-152304, an antenna for a mobile radio communication and acommunication portion are located at different portions and areconnected to each other through a coaxial cable.

Further, there has been proposed various circuits in each of which anantenna for a mobile communication for receiving a radio wave of amicrowave band is constituted by a micro strip line and integrated witha communication portion for processing the received signal. One is acircuit in which an antenna portion and an integrated circuitconstituting a communication portion are separately fabricated and thenintegrated as described in JP-A-63-316905. Another is a circuit in whichan antenna constituted by a micro strip line and a communication portionconstituted by a semiconductor circuit are formed on the same majorsurface of a substrate as described in JP-A-1-112827.

In the circuit described in JP-A-2-152304, since the coaxial cable isused to connect the antenna for the mobile communication and thecommunication portion, a radio frequency (RF) signal is attenuated dueto a signal loss in the coaxial cable, thereby an efficiency of thecommunication portion degrades.

Further, the circuit described in JP-A-63-316905 has the disadvantagesuch that, since material of the communication portion, i.e.,semiconductor material is different from material of the antennaportion, i.e., conductive material, it is required, in an integratingprocess of the materials, to provide a conductive layer at a rearsurface of the communication portion and to-utilize an adhesive solder,thereby complicating an assembling process of the circuit.

The circuit described in JP-A-1-112827 is advantageous in that signalloss of an RF signal can be decreased and the circuit can beminiaturized and light-weighted since the antenna and the communicationportion are integrally formed. However, this circuit has thedisadvantage such that since both the antenna and the communicationportion are located on the same surface, a radio wave having the samefrequency of that from the antenna is transmitted from the communicationportion and interferes with a radio wave transmitted from the antenna,so that this circuit can not be applied to one whose communicationportion has a modulating function.

Accordingly, it is an object of the present invention to provide animproved integrated multi-layered microwave circuit in which theaforementioned shortcomings and disadvantages encountered with the priorart can be eliminated.

More specifically, it is an object of the present invention to providean integrated multi-layered microwave circuit which can integrate anantenna portion and a communication portion by using a conventionalfabricating process of a circuit substrate and which is small in sizeand weight, less in signal loss and high in efficiency.

SUMMARY OF THE INVENTION

According to an aspect of the present invention, an integratedmulti-layered microwave circuit for use in a radio communicationterminal for a mobile station of a mobile radio communication systemincludes: an antenna portion formed by a micro strip line of conductivematerial; a communication portion for controlling a radio wave receivedand/or transmitted by and/or from the antenna portion; at least twodielectric layers laminated between the antenna portion and thecommunication portion; and at least one conductive layer disposedbetween the dielectric layers.

According to the thus constituted integrated multi-layered microwavecircuit of the present invention, since the antenna portion formed bythe micro strip line of conductive material and the communicationportion for controlling a radio wave received and/or transmitted byand/or from the antenna portion are laminated through at least twodielectric layers, the antenna portion and the communication portion areintegrated, so that the microwave circuit can be miniaturized andlight-weighted. Further, since the at least one conductive layer islaminated between the dielectric layers, the conductive layer serves asan antenna together with the micro strip line. Furthermore, since theantenna portion and the communication portion are disposed at oppositemajor surfaces of the laminated layers, that is, a substrate, theconductive layer shields a radio wave transmitted from and received bythe communication portion, so that the radio wave is prevented frombeing mixed as a noise into a radio wave transmitted from the antennaportion even when the communication portion has a modulating function.

Preferably, the integrated multi-layered microwave circuit furtherincludes a feeding portion for electrically connecting the antennaportion and the communication portion. The feeding portion preferablyincludes conductors formed by using the plating technique on an innersurface of the dielectric layers which forms a feeding via holepenetrating the dielectric layers between the antenna portion and thecommunication portion. The feeding via hole and the conductors form ashortest electrical path connecting the antenna portion and thecommunication portion, thereby signal loss therebetween can bedecreased.

Preferably, the conductive layer serves as a grounding layer, andconductors are formed by using the plating technique on an inner surfaceof the dielectric layer which forms a grounding via hole penetrating thedielectric layer between the grounding layer and the communicationportion, wherein the grounding layer and-the communication portion areelectrically connected through the conductors.

Preferably, the conductive layer serves as a power source layer, andconductors are formed by using the plating technique on an inner surfaceof the dielectric layer which forms a via hole for a power sourcepenetrating the dielectric layer between the power source layer and thecommunication portion, wherein the power source layer and thecommunication portion are electrically connected through the conductors.

Preferably, the integrated multi-layered microwave circuit furtherincludes another conductive layer, wherein one of the conductive layersserves as a grounding layer and the other serves as a power sourcelayer.

Preferably, the antenna portion includes at least one radiator fortransmitting and/or receiving a radio wave, and a phase shifterconnected between the radiator and the feeding portion for changing aphase of the radio wave transmitted and/or received by the radiator. Aradiation directivity of the antenna portion can be controlled bychanging a phase of a radio wave by the phase shifter.

Preferably, the phase shifter is constituted by the micro strip line,and a length of the micro strip line is adjusted depending on a locationof a mobile where the radiator is mounted so that a desired radiationdirectivity of the antenna portion is obtained. Since the phase shifteris constituted by the micro strip line, constructions of the microwavecircuit can be simplified.

Preferably, the communication portion includes a circuit patternconstituted by conductive material, a receiving portion for demodulatinga received radio wave and converting it into information data, atransmitting portion for modulating the information data into a radiowave to be transmitted, a shared portion connected to the feedingportion for separating the received radio wave from the radio wave to betransmitted, an oscillating portion for supplying an oscillation signalto the receiving portion and the transmitting portion, and an interfaceportion for exchanging the information data obtained by the receivingportion and the information data to be transmitted from the transmittingportion with an external circuit. Further, the shared portion preferablyincludes a filter.

Preferably, the integrated multi-layered microwave circuit furtherincludes a microcomputer for controlling devices mounted on a mobilebased on received information and/or information to be transmitted.Further, the microcomputer preferably outputs control data to acentralized control portion for controlling the devices mounted on thevehicle, whereby the microwave circuit can be further miniaturized andlight-weighted.

Preferably, the integrated multi-layered microwave circuit furtherincludes another conductive layer and another dielectric layer, whereinthe conductive layers and the dielectric layers are laminatedalternately, and wherein at least an adjacent pair of the conductivelayers and the dielectric layer sandwiched therebetween constitute acapacitor which constitutes at least a part of the shared portion or thefilter for separating the received radio wave from the radio wave to betransmitted. Thus, the number of parts required for the microwavecircuit can be decreased and so the microwave circuit can be furtherminiaturized and light-weighted.

Preferably, at least a side wall of the microwave circuit is covered byconductive material. Thus, a radio wave generated by the communicationportion is prevented from being leaked from the side wall of themicrowave circuit and being mixed as a noise into a radio wavetransmitted and received by the antenna portion.

According to another aspect of the present invention, a method offabricating an integrated multi-layered microwave circuit includes thesteps of: (a) forming conductive layers on both major surfaces of onedielectric layer; (b) forming circuit patterns in the conductive layers;(c) pressing other dielectric layers, on one major surface of each ofwhich a conductive layer is formed, to both major surfaces of the onedielectric layer having the circuit patterns thereon so that theconductive layers and the dielectric layers are integrally laminatedalternately to thereby form a substrate; (d) forming circuit patterns inthe conductive layers which are formed on the other dielectric layers atboth major surfaces of the substrate; (e) repeatedly performing thesteps (c) and (d) for a predetermined times; (f) forming via holes inthe substrate; and (g) forming conductors by using the plating techniqueon an inner surface of the substrate which forms each of the via holesto thereby form the substrate for the integrated multi-layered microwavecircuit.

According to still another aspect of the present invention, a method offabricating an integrated multilayered microwave circuit includes thesteps of: forming conductive layers on major surfaces of a plurality ofdielectric layers; forming circuit patterns in the conductive layers;pressing the plurality of dielectric layers having the circuit patternsso that the conductive layers and the dielectric layers are integrallylaminated alternately to thereby form a substrate; forming via holes inthe substrate; and forming conductors by using the plating technique onan inner surface of the substrate which forms each of the via holes tothereby form the substrate for the integrated multi-layered microwavecircuit.

According to the method of fabricating the integrated multi-layeredmicrowave circuit of the present invention, it is possible to easilyform the micro strip line constituting the radiator or the phaseshifter, the circuit pattern of the communication portion, and theconductive layer by utilizing the conventional fabricating process of acircuit substrate.

The preceding and other objects, features, and advantages of the presentinvention will become apparent from the following detailed descriptionof illustrative embodiments thereof when read in conjunction with theaccompanying drawings, in which like reference numerals are used toidentify the same or similar parts in the several views.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a schematic sectional view of an integrated multi-layeredmicrowave circuit according to a first embodiment of the presentinvention;

FIG. 2A is a schematic plan view of the integrated multi-layeredmicrowave circuit of FIG. 1 illustrating construction of an antennaportion thereof;

FIG. 2B is a schematic plan view of the integrated multi-layeredmicrowave circuit of FIG. 1 illustrating construction of a communicationportion thereof;

FIG. 3A is a functional block diagram illustrating the antenna portionof the integrated multi-layered microwave circuit of FIG. 1;

FIG. 3B is a functional block diagram illustrating the communicationportion of the integrated multi-layered microwave circuit of FIG. 1;

FIG. 4 is a schematic diagram illustrating a communication system whichcommunicates among the integrated multi-layered microwave circuit ofFIGS. 2A and 2B, a microcomputer, a navigator (centralized controlsystem), and devices mounted on a vehicle;

FIG. 5 is a schematic plan view illustrating another example of thecommunication portion of the integrated multi-layered microwave circuitof FIG. 1 in which a microcomputer is formed on a substrate thereof;

FIG. 6 is a partially cutaway view in perspective illustrating a metalcasing in which the integrated multi-layered microwave circuit of FIGS.2A and 2B is incorporated;

FIG. 7 is a schematic diagram illustrating a first method of fabricatingthe substrate used in the integrated multi-layered microwave circuit ofthe embodiment;

FIG. 8 is a schematic diagram illustrating a second method offabricating the substrate used in the integrated multi-layered microwavecircuit of the embodiment;

FIG. 9A is a schematic diagram illustrating external locations of anautomobile body at which the integrated multi-layered microwave circuitof the embodiment may be mounted;

FIG. 9B is a schematic diagram illustrating internal locations of anautomobile body at which the integrated multi-layered microwave circuitof the embodiment may be mounted;

FIGS. 10A to 10H are schematic diagrams illustrating radiation patternsof the integrated multi-layered microwave circuits of the presentinvention located at the portions shown in FIGS. 9A and 9B,respectively;

FIGS. 11A and 11B are schematic diagrams illustrating coordinate axes ofthe radiation pattern of the integrated multi-layered microwave circuitof the present invention as to the automobile;

FIG. 12 is a schematic plan view of the integrated multi-layeredmicrowave circuit of FIG. 1 illustrating a modification of an antennaportion thereof;

FIG. 13 is a schematic plan view of the integrated multi-layeredmicrowave circuit of FIG. 1 illustrating another modification of anantenna portion thereof;

FIG. 14 is a schematic plan view of an integrated multi-layeredmicrowave circuit according to a second embodiment illustratingconstruction of an antenna portion thereof;

FIG. 15 is a schematic plan view of the integrated multi-layeredmicrowave circuit according to the second embodiment illustratingconstruction of a grounding layer (conductive layer) thereof;

FIG. 16 is a schematic plan view of the integrated multi-layeredmicrowave circuit according to the second embodiment illustratingconstruction of a power source layer (conductive layer) thereof;

FIG. 17 is a schematic plan view of the integrated multi-layeredmicrowave circuit according to the second embodiment illustratingconstruction of a communication layer thereof;

FIG. 18 is a schematic perspective sectional view of the integratedmulti-layered microwave circuit of the second embodiment taken along aline XVIII--XVIII in FIG. 14;

FIG. 19A is a schematic sectional view illustrating a portion of FIG. 18constituted by conductive portions 50A, 51A and a dielectric layerdisposed therebetween; and

FIG. 19B is a schematic diagram illustrating an equivalent circuit ofthe portion shown in FIG. 19A.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

An integrated multi-layered microwave circuit according to the firstembodiment of the present invention will now be described with referenceto FIGS. 1 to 13, in which case the present invention is applied to aradio communication terminal for a mobile station which is used in theVICS utilizing a microwave of not less than 1.0 GHz, for example.

FIG. 1 shows a sectional view of an integrated multi-layered microwavecircuit according to the first embodiment. Referring to FIG. 1, anintegrated multi-layered microwave circuit 40 (FIG. 4) of the firstembodiment includes a substrate 16 constituted of three dielectriclayers 4, 6 and 14 and four conductive layers 1, 3, 12 and 17, in whichthe dielectric layers and the conductive layers are arrangedalternately. The conductive layer located on one major surface of thesubstrate 16 forms a micro strip line 1 to thereby constitute a antennaportion 21. The conductive layer located at the other major surface ofthe substrate 16 forms a circuit pattern 17 having a grounding line 11and a power source line 15. The circuit pattern 17 constitutes acommunication portion 27 together with discrete parts 7, 8, 9 and 10incorporated in the circuit pattern 17. One of the two intermediateconductive layers of the substrate 16 forms a grounding layer 3 and theother thereof forms a power source layer 12.

In the substrate 16, a feeding via hole 2 is formed so as to penetratethe dielectric layers between the antenna portion 21 and thecommunication portion 27. Conductors 2a are formed on an inner surfaceof the dielectric layers forming the feeding via hole 2 by using theplating technique so that the antenna portion 21 and the communicationportion 27 are electrically connected by the conductors 2a. The feedingvia hole 2 and the conductors 2a form a feeding portion. The conductors2a serve to transmit a signal between the antenna portion 21 includingthe micro strip line 1 and the communication portion 27 including thecircuit pattern 17 and the discrete parts 7, 8, 9 and 10. The feedingvia hole 2 and the conductors 2a form a shortest path for connecting theantenna portion 21 and the communication portion 27, thereby decreasingsignal loss therebetween.

A grounding via hole 13 is also formed in the substrate 16 to penetratethe dielectric layers between the grounding layer 3 and thecommunication portion 27. Conductors 13a are formed on an inner surfaceof the dielectric layers forming the ground via hole 13 by using theplating technique to thereby electrically connect the grounding layer 3and the grounding line 11 by the conductors 13a. Further, a via hole 5for a power source is formed in the substrate to penetrate thedielectric layers between the power source layer 12 and thecommunication portion 27. Conductors 5a are formed on an inner surfaceof the dielectric layers forming the via hole for the power source byusing the plating technique to thereby electrically connect the powersource layer 12 and the power source line 15.

The configurations of the micro strip line and the circuit pattern shownin FIG. 1 are typical examples and various modifications inconfigurations thereof may be made. Further, the substrate isillustrated to be thick in FIG. 1 so as to facilitate a betterunderstanding of the embodiment, but a thickness of the substrate isvery thin in fact.

The micro strip line 1 is formed by partially etching away theconductive layer located at the one major surface of the substrate 16.Similarly, the circuit pattern 17 is formed by partially etching awaythe conductive layer located at the other major surface of the substrate16. The micro strip line I serves as a radiator together with thegrounding layer 3. In this regard, an electronic radio wave transmittedfrom and received by the micro strip line 1 is not influenced by anelectronic radio wave radiated from the discrete parts 7 to 10 of thecommunication portion 27 since the radiated radio wave is shielded bythe grounding layer 3.

Concrete constructions and functions of the antenna portion 21 and thecommunication portion 27 of the integrated multi-layered microwavecircuit 40 will be described. As shown in FIGS. 2A and 3A, the antennaportion 21 includes a feeding land 22 connected to the feeding via hole2, three circular radiators 23, 24 and 25 formed by the micro strip line1, and a phase shifter 26 formed by the micro strip line 1 forconnecting the respective radiators to the feeding land 22. Phases ofsignals radiated from the respective radiators 23 to 25 can be changedby changing a length of the micro strip line constituting the phaseshifter 26, thereby radiation directivity of the antenna portion 21 canbe controlled.

Since the thus constituted antenna portion 21 is formed by the microstrip line and has a flat configuration with no projection, there is noproblem in mounting the discrete parts 7, 8, 9 and 10 on thecommunication portion 27, so that they can be arranged easily thereon.Further, since the discrete parts 7, 8, 9 and 10 are incorporated in thecommunication portion 27, the microwave circuit can be miniaturized.While the phase shifter of the embodiment is formed by the micro stripline so that a phase of the radiated signal is changed by changing thelength of the micro strip line, the phase shifter may be formed by usinga diode or the like which can electrically change the phase of theradiated signal.

As shown in FIGS. 2B and 3B, at the communication portion 27, there aremounted, on the circuit pattern 17, a feeding land 28, a common useportion or shared portion 29, a receiving portion 30 having apreamplifier integrated circuit (IC) 30A serving as a receiver and an IC30B serving as a demodulator, a transmitting portion 31 having a poweramplifier IC 31A serving as a transmitter and an IC 31B serving as amodulator, an oscillating portion 34 having an oscillator 32 for thereceiver and an oscillator 33 for the transmitter, an interface (I/F)circuit 35 having a phase locked loop (PLL) IC for controlling theoscillating portion 34 and an I/F IC, and a connector 36. The I/Fcircuit 35 and the connector 36 constitute an I/F portion 37.

The feeding land 28 is connected to the feeding via hole 2 as well asthe feeding land 22 of the antenna portion 21 and further connected tothe shared portion 29. The shared portion 29 is a kind of filter forseparating a received radio wave from a transmitting radio wave, and itcan be miniaturized when formed by ceramics of a high relativepermittivity, for example.

The receiving portion 30 is a circuit portion which demodulates areceived radio wave to obtain communication information of an analogform and converts the analog information into a digital signal tothereby output it. The transmitting portion 31 is a circuit portionwhich converts a digital signal of inputted communication information tobe transmitted into an analog signal and demodulates the analog signalinto a radio wave to be transmitted. These functions of analog todigital conversion and vice versa are performed by the IC 30B and the IC31B, respectively.

The oscillator 34 is a frequency synthesizer for supplying a localoscillation signal to the receiving portion 30 and the transmittingportion 31 under the control of an external microcomputer etc. The I/Fcircuit 35 is a circuit portion which communicates with the externalmicrocomputer etc. as to data in a digital form such as data demodulatedby the receiving portion 30, data to be modulated by the transmittingportion 31, and data for controlling the oscillating portion 34. Theconnector 36 is a connecting portion which is used to connect themicrowave circuit with a digital device such as the externalmicrocomputer.

An example of a communication system in which devices mounted on avehicle are controlled in accordance with information from theintegrated multi-layered microwave circuit 40 will be explained withreference to FIG. 4.

Referring to FIG. 4, the integrated multi-layered microwave circuit 40according to the first embodiment communicates control data of a digitalsignal with an external microcomputer 41 mounted on the vehicle throughthe I/F portion 37 shown in FIGS. 2B and 3B of the communication portion27. The microcomputer 41 communicates control data of a digital signalwith a navigator (centralized control system) 42 mounted on the vehicle,and controls through the navigator 42 devices mounted on the vehiclesuch as a cathode ray tube (CRT) 43, a compact disc read only memory(CD-ROM) 44, an audio playback unit 45, and an air conditioner 46. Thepower source layer 12 and the grounding layer 3 (FIG. 1) of theintegrated multi-layered microwave circuit 40 of FIG. 1 are connected topower source and a ground of the microcomputer 41, respectively.

The CRT 43 is a device for displaying states of the CD-ROM 44, the audioplayback unit 45 and the air conditioner 46 or the like. FIG. 4 is aconceptional view and so in practice the microcomputer 41 and thenavigator (centralized control system) 42 are disposed in a consolepanel of the vehicle mounting the CRT 43 and the audio playback unit 45.The mounting location and the radiation directivity of the integratedmulti-layered microwave circuit 40 in the vehicle will be describedlater.

The integrated multi-layered microwave circuit 40 may be located closeto the microcomputer 41 or the navigator 42. For example, as shown inFIG. 5, the microcomputer 41 may be integrally formed on the substrateof the integrated multi-layered microwave circuit 40, thereby size andweight of the radio communication terminal for the mobile station can befurther decreased. In this case, the microcomputer 41 is disposedbetween the I/F portion SY and an area having the receiving portion 30,oscillating portion 34 and transmitting portion 31. Then, themicrocomputer 41 carries out a digital communication with the externalnavigator 42 through the I/F portion 37.

FIG. 6 is a partially cutaway perspective view illustrating a metalcasing 47 in which the integrated multi-layered microwave circuit 40 ofthe embodiment is incorporated. Referring to FIG. 6, a front surface ofthe substrate of the integrated multi-layered microwave circuit 40constitutes the antenna portion 21 which transmits and receives a radiowave through the radiators 23, 24 and 25, and a rear surface thereofconstitutes the communication portion 27 which performs a signalprocessing. The metal casing 47 is provided with a plastic lid 48 forprotecting the circuit in the casing. In the metal casing 47, a powersupply circuit or a substrate mounting a control circuit etc.incorporating the microcomputer 41 may be disposed close to theintegrated multi-layered microwave circuit. Alternatively, the substrateintegrally mounting the integrated multi-layered microwave circuit 40and the microcomputer 41 may be disposed in the casing.

When the integrated multi-layered microwave circuit 40 is accommodatedin the metal casing 47 in this manner, at least side walls of outerperiphery of the substrate 16 are covered by conductive material, sothat a radio wave generated at the communication portion 27 is preventedfrom leaking from the side walls of the substrate and interfering with aradio wave transmitted from and received by the antenna portion 21 asnoise. In order to change the radiation directivity of the antennaportion 21, an orientation of the metal casing 47 may be changed, but itis more preferable to control the radiation directivity of the antennaportion by adjusting the phase shifter 26 as described above dependingon a location where the metal casing is mounted.

Fabricating methods of the integrated multi-layered microwave circuit 40of the embodiment will be described with reference to FIGS. 7 and 8.Since there are two separate methods in fabricating the substrate 16 ofthe integrated multi-layered microwave circuit 40, they will beexplained separately with reference to FIGS. 7 and 8, respectively.

Firstly, the first fabricating method will be described with referenceto FIG. 7. As shown in FIG. 7, at first, conductive layers 3a and 12aare formed at both major surfaces of the dielectric layer 4 at step 101.Then, the conductive layers 3a and 12a are selectively etched away toform circuit patterns on the both major surfaces of the dielectric layer4, respectively, in step 102. The conductive layers forming thesecircuit patterns constitute the grounding layer 3 and the power sourcelayer 12, respectively.

In step 103, the dielectric layer 6 and the dielectric layer 14 on whichconductive layer 17a and 1a are formed in the same manner as step 101,respectively, are pressed on both major surfaces of the dielectric layer4 having the above-described circuit pattern, respectively, therebyforming the substrate 16 having the three dielectric layers and the fourconductive layers. In this case, the dielectric layers and theconductive layers are pressed so as to be disposed alternately.

Then, in step 104, the feeding via hole 2, the via hole 5 for the powersupply and the grounding via hole 13 are formed in the substrate 16, andthen the conductors 2a, 5a and 13a are formed on the inner surfaces ofthe dielectric layers forming these via hole 2, 5 and 13 by using theplating technique, respectively.

Circuit patterns are formed in the conductive layers 1a and 17a on bothmajor surfaces of the substrate by the etching technique, respectivelyin step 105. These conductive layers in which the circuit patterns areformed constitute the micro strip line 1 of the antenna portion 21 andthe circuit pattern 17 of the communication portion 27. Lastly, theresist processing is performed on the circuit pattern 17 to form aprotecting film thereof in step 106, then the discrete parts 7 to 10(see FIG. 1) are arranged in the communication portion 27 to therebyform the integrated multi-layered microwave circuit 40.

The second fabricating method will be described with reference to FIG.8. As shown in FIG. 8, firstly, in step 201, conductive layers 3a and12a are formed at both major surfaces of the dielectric layer 4 in thesame manner as step 101, and further conductive layers 1a and 17a areformed on one major surfaces of the dielectric layers 14 and 6,respectively.

Then, the conductive layers 3a and 12a on both major surfaces of thedielectric layer 4, the conductive layer 1a on the dielectric layer 14,and the conductive layer 17a of the dielectric layer 6 are selectivelyetched away to form circuit patterns in step 202. Among these conductivelayers in which the circuit patterns are thus formed, the conductivelayers on both major surfaces of the dielectric layer 4 constitute thegrounding layer 3 and the power source layer 12, that of the dielectriclayer 14 constitutes the micro strip line 1 of the antenna portion 21,and that of the dielectric layer 6 constitutes the circuit pattern 17 ofthe communication portion 27.

Then, in step 203, the dielectric layer 6 and the dielectric layer 14 oneach of which the circuit pattern is formed are pressed on both majorsurfaces of the dielectric layer 4, respectively, thereby forming thesubstrate 16 having the three dielectric layers and the four conductivelayers. In this case, the dielectric layers and the conductive layersare pressed so as to be disposed alternately.

Then, in step 204, the feeding via hole 2, the via hole 5 for the powersupply and the grounding via hole 13 are formed in the substrate 16, andthen the conductors 2a, 5a and 13a are formed on the inner surfaces ofthe dielectric layers forming these via hole 2, 5 and 13 by using theplating technique, respectively. Lastly, the resist processing isperformed on the circuit pattern 17 to form a protecting film thereof instep 205, then the discrete parts 7 to 10 (see FIG. 1) are arranged inthe communication portion 27 to thereby form the integratedmulti-layered microwave circuit 40.

In each of the first and second fabricating methods, each of the microstrip line 1 constituting the antenna portion 21, the circuit pattern 17of the communication portion, the grounding layer 3, and the powersource layer 12 can be formed easily by utilizing the conventionalfabricating process of a circuit substrate, so that the integratedmulti-layered microwave circuit 40 can be fabricated easily.

Then, the explanation will be made with reference to FIGS. 9A to 11Babout locations of an automobile at which the integrated multi-layeredmicrowave circuit of the embodiment can be mounted and radiationdirectivity thereof. As shown in FIG. 9A, the integrated multi-layeredmicrowave circuit of the embodiment may be located at an exteriorportion of an automobile body such as a position within one of at leasttwo side mirrors 101a and 101b, a position 102 on a roof top or a buriedposition within the roof top, or a right or left end portion 103 of atail gate.

Alternatively, as shown in FIG. 9B, the integrated multi-layeredmicrowave circuit of the embodiment may be located at an interiorportion of the automobile such as a position within a room mirror 104, aposition 105 on a dash board or a buried position within the dash board,or a position 106 on a rear tray or a buried position within the reartray. A location where the integrated multi-layered microwave circuit ofthe present invention is mounted may be suitably determined depending ona configuration of an automobile and an efficiency of the microwavecircuit.

The antenna portion of the integrated multi-layered microwave circuitlocated at any portion shown in FIGS. 9A and 9B has the radiationdirectivity that there is generally no gain at lower direction of theautomobile to thereby prevent the influence of a reflection wave fromthe ground.

The explanation will be made referring to FIGS. 10A to 10H aboutradiation patterns of the integrated multi-layered microwave circuits ofthe present invention located at the portions shown in FIGS. 9A and 9B.In this case, coordinate axes of the radiation pattern as to theautomobile will be defined as shown in FIGS. 11A and 11B. The radiationpattern of the integrated multi-layered microwave circuit located at theposition 101a within the door mirror will be that shown in FIGS. 10A and10B. Namely, the radiation pattern will be high in gain to a frontdirection of the automobile (a positive direction of an x-axis) and anupper direction of the automobile (a positive direction of a z-axis) butlow to a rear direction (a negative direction of the x-axis) as shown inFIG. 10A, and further slightly high at a left side of the automobile (apositive direction of a y-axis) when compared with a right side thereofdue to the presence of a side wall of the automobile to thereby exhibitnot symmetric pattern as shown in FIG. 10B.

The radiation pattern of the integrated multi-layered microwave circuitlocated at the position 101b within the door mirror will be same as thatat the position 101a except that the radiation pattern corresponding tothat of FIG. 10B is inverse to that of FIG. 10B to the y-axis direction.

The radiation pattern of the integrated multi-layered microwave circuitlocated at each of the roof top position 102 and the end portion 103 ofthe tail gate will be high in gain generally to the upper direction ofthe automobile (the positive direction of the z-axis) and exhibit asymmetric pattern as shown in FIGS. 10C and 10D.

The radiation pattern of the integrated multi-layered microwave circuitlocated at the position 104 within the room mirror will be same as thatat the position 101a or 101b to the longitudinal or x-axis direction ofthe automobile as shown in FIG. 10E, but exhibit a symmetric pattern tothe direction perpendicular to the longitudinal direction or y-axisdirection as shown in FIG. 10F due to the presence of the side walls ofthe automobile.

The radiation pattern of the integrated multi-layered microwave circuitlocated at the position of the dash board 105 will be low in gain to theupper direction of the automobile (the positive direction of the z-axis)and high in gain to the front direction of the automobile (the positivedirection of the x-axis) as shown in FIG. 10G since the circuit islocated at the interior of the automobile, and further exhibit asymmetric pattern to the direction perpendicular to the longitudinaldirection of the automobile or y-axis direction as shown in FIG. 10H.

The radiation pattern of the integrated multi-layered microwave circuitlocated at the position of the rear tray 106 is same as that located atthe dash board 105 except that the radiation pattern corresponding tothat of FIG. 10G is inverse to that of FIG. 10G to the longitudinaldirection of the automobile in a manner that the gain is high to therear direction of the automobile (the negative direction of the x-axisdirection).

The radiation directivity of the integrated multi-layered microwavecircuit located at these positions can be controlled by adjusting thephase shifters of the antenna portion. That is, a phase of a radio waveradiated from the radiators can be changed when the lengths of the phaseshifters constituted by the micro strip line is changed. Further, theradiation directivity of the antenna portion can be changed depending onthe location where the integrated multi-layered microwave circuit ismounted, thereby a suitable radio communication area can be assured.

FIGS. 12 and 13 show modifications of the antenna portion of theembodiment. In the antenna portion of FIG. 12, the radiator constitutesa circular patch antenna 23a, while in the antenna portion of FIG. 13,the radiator constitutes a rectangular patch antenna 23b. In each of themodifications, the radiator (antenna portion) is directly connected tothe feeding via hole 2 without providing the phase shifters. Thesemodifications are employed when the integrated multi-layered microwavecircuit is not required to have significant radiation directivity, andthe circuit of these modifications can be manufactured easily since thephase shifters of complicated configurations are not required.

As described above, in accordance with the embodiment, since the antennaportion 21 and the communication portion 27 are integrally mounted onthe both major surfaces of the substrate, the integrated multi-layeredmicrowave circuit can be miniaturized and light-weighted. Further, sincethe antenna portion 21 and the communication portion 27 are connectedwith each other through the feeding via hole 2 and the conductors 2a,the antenna portion 21 and the communication portion 27 are connectedthrough a shortest electrical path and so the integrated multi-layeredmicrowave circuit of the embodiment can decrease signal loss.Furthermore, a radio wave generated from the communication portion 27 isshielded by the conductive layer, that is, the grounding layer 3 or thepower source layer 12, so that an electronic radio wave radiated fromthe communication portion 27 is prevented from being mixed into a radiowave transmitted from and received by the antenna portion 21, therebythe integrated multi-layered microwave circuit of the embodiment canprovide a higher efficiency.

Furthermore, since the microcomputer 41 and the integrated multi-layeredmicrowave circuit 40 are integrated, the radio communication terminalfor the mobile station can be further miniaturized and light-weighted.Further, since the integrated multi-layered microwave circuit isaccommodated in the metal casing 47, so that a radio wave generated atthe communication portion 27 is prevented from leaking from the sidewalls of the substrate and interfering with a radio wave transmittedfrom and received by the antenna portion 21 as noise.

Further, the integrated multi-layered microwave circuit 40 can bemanufactured easily by employing the fabricating process of a printedcircuit similar to the conventional process.

Furthermore, since a phase of a radio wave radiated from the integratedmulti-layered microwave circuit can be changed by adjusting the phaseshifters, the radiation directivity of the antenna portion can becontrolled depending on a location where the microwave circuit ismounted.

An integrated multi-layered microwave circuit according to the secondembodiment will be described with reference to FIGS. 14 to 19B.

The integrated multi-layered microwave circuit of the second embodimentis constituted in a manner that an antenna portion 50 shown in FIG. 14,a ground layer (conductive layer) 51 shown in FIG. 15, a power sourcelayer (conductive layer) 52 shown in FIG. 16, and a communicationportion 53 shown in FIG. 17 are laminated and then dielectric layers aredisposed therebetween. A process of fabricating the integratedmulti-layered microwave circuit of this embodiment is substantially thesame as that shown in FIG. 7 or 8.

Each of these layers is provided with grounding via holes 70 and viaholes 71 for a power source. The grounding via holes 70 are connected tothe grounding layer 51 but electrically insulated from the power sourcelayer 52. The via holes 71 for the power source are connected to thepower source layer 52 but electrically insulated from the groundinglayer 51.

In the antenna portion 50, an antenna 54, a phase shifter 54A, aconductive portion 50A and also a terminating resistor element 55 areformed by a micro strip line. The terminating resistor element 55 is achip resistor constituted by a printed circuit element of a thin film ora pressure membrane, and provided so as to decrease a voltage standingwave ratio (VSWR) viewed from the communication portion 53 to match withan input impedance of the communication portion 53, and also so as todecrease a VSWR viewed from the antenna portion 50 to match with anoutput impedance of the antenna portion 50. The terminating resistorelement 55 may be omitted when the constitution of the antenna portion50 is modified to perform impedance matching.

In the communication portion 53, receiving, transmitting, andoscillating portions are mounted on a circuit pattern as a receivingportion module 60, a transmitting portion module 61 and an oscillatingportion module 62, respectively. The grounding via hole 70 and the viahole 71 for the power source are formed in each of lands (conductivelayers) 60A, 61A and 62A provided at the respective modules so as topenetrate therethrough. Conductors are formed on an inner surface of thedielectric layers forming each of the grounding via holes 70 and the viaholes 71 for power supply by using the plating technique, and theconductors are connected to corresponding lands.

The communication portion 53 is further provided with an I/F circuit 72and a connector 73 having the same functions of those shown in FIG. 2.Further, in the communication portion, conductive portions of stripconfigurations 53A, 53B and 53C are aligned stepwise to form a series offlat conductors. The series of flat conductors constitute capacitive andinductive elements to serve as a band pass filter or a high pass filter.Namely, the series of flat conductors constituted by the conductorportions 53A to 53C constitute a part of a shared portion 63 forseparating a received radio wave from a radio wave to be transmitted.

The antenna portion 50 and the communication portion 53 are connectednot through such a feeding portion as shown in FIG. 1, butelectromagnetically coupled to each other through a distributed constantcircuit which is extended to a laminated direction of the substrate andformed by a coupling portion 56 of the antenna portion 50, a couplingportion 57 of the grounding layer 51, a coupling portion 58 of the powersource layer 52, and a coupling portion 59 of the communication portion53. The distributed constant circuit serves as a feeding portion. Thatis, as shown in FIG. 18, a conductive portion 50A of the antenna portion50, a conductive portion 51A of the grounding layer 51, a conductiveportion 52A of the power source layer 52, and a conductive portion 53Aof the communication portion 53 are aligned stepwise to a laminateddirection thereof through dielectric layers 75, 76 and 77 to form aseries of three-dimensional conductors. The series of three-dimensionalconductors constitute capacitive and inductive elements to serve as aband pass filter or a high pass filter. Namely, like the flat capacitiveand inductive elements constituted by the conductor portions 53A to 53C,the series of three-dimensional conductors constituted by the conductorportions 50A to 53A constitute a part of the shared portion 63 forseparating a received radio wave from a radio wave to be transmitted.

An example of an equivalent circuit of the series of three-dimensionalconductors constituted by the conductor portions 50A to 53A will bedescribed with reference to FIGS. 19A and 19B. Referring to FIG. 19A, ina portion constituted by the conductor portions 50A and 51A and thedielectric layer 75 disposed therebetween, if the conductor portion 50Aside and the conductor portion 51A side serve as input and outputterminals, respectively, the equivalent circuit of this portion will bethat shown in FIG. 19B. That is, in this equivalent circuit, the inputterminal is grounded through an inductive element L1 and a capacitiveelement C1 connected in parallel. Further, the input terminal isconnected to the output terminal through an inductive element L2 and acapacitive element C2 connected in series. The output terminal isgrounded through an inductive element L3 and a capacitive element C3connected in parallel. The equivalent circuit constitutes a K typeblock. Thus, an equivalent circuit of the series of three-dimensionalconductors shown in FIG. 18 will be that constituted by connecting threecircuits each similar to the π type block shown in FIG. 19B.

As described above, in accordance with the second embodiment, since theseries of flat conductors constituted by the conductor portions 53A to53C and the series of three-dimensional conductors constituted by theconductor portions 50A to 53A are utilized as the filters and serve asthe shared portion, the integrated multi-layered microwave circuit doesnot require discrete parts such as a dielectric filter. Thus, thisembodiment is advantageous in that the number of required parts can bedecreased, and the constructions can be simplified to furtherminiaturize and decrease in weight, and further cost reduction can beperformed. Further, a property of the filter can be arranged to exhibita steep band pass characteristic by suitably setting sizes of theconductive portions or dielectric constants of the dielectric layers.

While in each of the above-described embodiments, the number of theconductive layers including the antenna portion and the communicationportion is four, the number of the dielectric layers and the conductivelayers may be increased to constitute a three-dimensional microwavecircuit, thereby the number of the discrete parts can be decreased tofurther miniaturize the microwave circuit.

The micro strip line of the antenna portion may constitute a microwavecircuit such as an impedance matching circuit, a filter, or a powerdivider or directional coupler as well as the radiators and the phaseshifters.

As set out above, according to the present invention, since the antennaportion and the communication portion are integrally provided on bothmajor surfaces of the substrate, the integrated multi-layered microwavecircuit can be miniaturized and decreased in weight. Further, since theantenna portion is connected to the communication portion through thefeeding portion, the antenna portion is connected to the communicationportion through a shortest path, so that signal loss can be decreased.Further, since a radio wave generated from the communication portion isshielded by the conductive layer, an electronic radio wave radiated fromthe communication portion is prevented from being mixed into a radiowave transmitted from and received by the antenna portion, thereby theintegrated multi-layered microwave circuit of the present invention canprovide a higher efficiency.

Furthermore, since the integrated multi-layered microwave circuit andexternal circuits such as the microcomputer are closely or integrallydisposed, the radio communication terminal for the mobile station can beminiaturized and light-weighted. Further, since at least the externalside walls of the integrated multi-layered microwave circuit are coveredby the conductor, a radio wave generated at the communication portion isprevented from leaking from the side walls of the microwave circuit.

Furthermore, radiation directivity of the antenna portion can becontrolled depending on a location of the mobile where the integratedmulti-layered microwave circuit is mounted.

Furthermore, since the three-dimensional distributed constant circuitconstitutes at least a part of the shared portion or the filter, thenumber of parts required for the integrated multi-layered microwavecircuit can be decreased, thereby the microwave circuit can be furtherminiaturized and light-weighted. Further, the filter can be arranged toexhibit a steep band pass characteristic by suitably setting a propertythereof.

Furthermore, the integrated multi-layered microwave circuit can befabricated easily by employing the fabricating process of a printedcircuit similar to the conventional process.

Having described the preferred embodiments of the invention withreference to the accompanying drawings, it is to be understood that theinvention is not limited to those precise embodiments and that variouschanges and modifications thereof could be effected by one skilled inthe art without departing from the spirit or scope of the invention asdefined in the appended claims.

What is claimed is:
 1. An integrated multi-layered microwave circuit foruse in a radio communication terminal for a mobile station of a mobileradio communication system, comprising:antenna circuit formed by a microstrip line of conductive material; communication circuit for controllinga radio wave which can be received and transmitted by and from saidantenna circuit; at least two dielectric layers laminated between saidantenna circuit and said communication circuit; at least one conductivelayer disposed between said dielectric layers; further comprising afeeding portion disposed between said antenna circuit and saidcommunication circuit, signals being transmitted between said antennacircuit and said communication circuit; and wherein said communicationcircuit includes a circuit pattern constituted by conductive material, areceiving portion for demodulating a received radio wave and convertingit into information data, a transmitting portion for modulating theinformation data into a radio wave to be transmitted, a shared portionconnected to said feeding portion for separating the received radio wavefrom the radio wave to be transmitted, an oscillating portion forsupplying an oscillation signal to said receiving portion and saidtransmitting portion, and an interface portion for exchanging theinformation data obtained by said receiving portion and the informationdata to be transmitted from said transmitting portion with an externalcircuit.
 2. An integrated multi-layered microwave circuit according toclaim 1, wherein said feeding portion includes conductors formed byusing a plating technique on an inner surface of said dielectric layerswhich forms a feeding via hole penetrating said dielectric layersbetween said antenna circuit and said communication circuit.
 3. Anintegrated multi-layered microwave circuit according to claim 1, whereinsaid conductive layer serves as a grounding layer.
 4. An integratedmulti-layered microwave circuit according to claim 3, further comprisingconductors formed by using the plating technique on an inner surface ofsaid dielectric layer which forms a grounding via hole penetrating saiddielectric layer between said grounding layer and said communicationcircuit, wherein said grounding layer and said communication circuit areelectrically connected through said conductor.
 5. An integratedmulti-layered microwave circuit according to claim 1, wherein saidconductive layer serves as a power source layer.
 6. An integratedmulti-layered microwave circuit according to claim 5, further comprisingconductors formed by using the plating technique on an inner surface ofsaid dielectric layer which forms a via hole for a power sourcepenetrating said dielectric layer between said power source layer andsaid communication circuit, wherein said power source layer and saidcommunication circuit are electrically connected through said conductor.7. An integrated multi-layered microwave circuit according to claim 1,further comprising another conductive layer, wherein one of saidconductive layers serves as a grounding layer and the other serves as apower source layer.
 8. An integrated multi-layered microwave circuitaccording to claim 1, wherein said antenna circuit includes at least oneradiator for at least one of transmitting and receiving a radio wave,and a phase shifter connected between said radiator and said feedingportion for changing a phase of the radio wave which can be transmittedand received by said radiator.
 9. An integrated multi-layered microwavecircuit according to claim 8, wherein said phase shifter is constitutedby a micro strip line, and a length of said micro strip line is adjusteddepending on a location of a mobile where said radiator is mounted sothat a desired radiation directivity of said antenna circuit isobtained.
 10. An integrated multi-layered microwave circuit according toclaim 1, wherein said shared portion includes a filter.
 11. Anintegrated multi-layered microwave circuit according to claim 1, furthercomprising a microcomputer controlling devices mounted on at least oneof a mobile based on received information and information to betransmitted.
 12. An integrated multi-layered microwave circuit accordingto claim 11, wherein said microcomputer outputs control data to acentralized control means for controlling the devices mounted on themobile.
 13. An integrated multi-layered microwave circuit according toclaim 1, further comprising another conductive layer and anotherdielectric layer, wherein said conductive layers and said dielectriclayers are laminated alternately, and wherein at least an adjacent pairof said conductive layers and said dielectric layer sandwichedtherebetween constitute a capacitor which constitutes at least a part ofa shared portion or a filter for separating the received radio wave fromthe radio wave to be transmitted.
 14. An integrated multi-layeredmicrowave circuit according to claim 1, wherein at least a side wall ofsaid microwave circuit is covered by conductive material.
 15. Anintegrated multi-layered microwave circuit, comprising:communicationmeans for controlling reception and/or transmission of a radio wave atand/or from an antenna layer which is provided at one major surface ofat least one dielectric layer, said communication portion being providedat the other major surface of said dielectric layer; a feeding portionfor electrically connecting said antenna layer and said communicationmeans; and wherein said communication circuit includes a circuit patternconstituted by conductive material, a receiving portion for demodulatinga received radio wave and converting it into information data, atransmitting portion for modulating the information data into a radiowave to be transmitted, a shared portion connected to said feedingportion for separating the received radio wave from the radio wave to betransmitted, an oscillating portion for supplying an oscillation signalto said receiving portion and said transmitting portion, and aninterface portion for exchanging the information data obtained by saidreceiving portion and the information data to be transmitted from saidtransmitting portion with an external circuit.
 16. An integratedmulti-layered microwave circuit for use in a radio communicationterminal for a mobile station of a mobile radio communication system,comprising:antenna means formed by a micro strip line of conductivematerial; communication means for controlling a radio wave which can bereceived and transmitted by and from said antenna means; at least twodielectric layers laminated between said antenna means and saidcommunication means; at least one conductive layer disposed between saiddielectric layers; further comprising a feeding portion disposed betweensaid antenna means and said communication means, signals beingtransmitted between said antenna means and communication means; andwherein said communication means includes a circuit pattern constitutedby conductive material, a receiving portion for demodulating a receivedradio wave and converting into information data, a transmitting portionfor modulating the information data into a radio wave to be transmitted,a shared portion connected to said feeding portion for separating thereceived radio wave from the radio wave to be transmitted, anoscillating portion for supplying an oscillation signal to saidreceiving portion and said transmitting portion, and an interfaceportion for exchanging the information data obtained by said receivingportion and the information data to be transmitted from saidtransmitting portion with an external circuit.
 17. An integratedmulti-layered microwave circuit for use in a radio communicationterminal for a mobile station of a mobile radio communication system,comprising:a dielectric layer; antenna formed by a microstrip ofconductive material on one surface of said dielectric layer; atransmitting receiving circuit formed on the other surface of saiddielectric layer; a grounding layer and a power source layer formed insaid dielectric layer arranged between said antenna and saidtransmitting receiving circuit; a feeding via hole connecting saidantenna and said transmitting receiving circuit; a grounding via holeconnecting said transmitting receiving circuit and said grounding layer;a via hole for a power source connecting said transmitting receivingcircuit and said power source layer.